F.B.I. agents on Thursday searched two houses owned by a close aide to Mayor Eric Adams of New York City, according to two people with knowledge of the matter.

The searches of the properties owned by the aide, Winnie Greco, occurred as part of an investigation being conducted with prosecutors from the U.S. attorney’s office in Brooklyn, the people said. Agents executed at least one other search warrant at a third location on Thursday morning, but it was unclear where, the people said.

It was also unclear what the investigation was focused on or whether it was related to Mr. Adams, who has been the subject of a separate criminal inquiry by the U.S. attorney’s office in Manhattan.

An F.B.I. spokesman said Thursday that the bureau “was conducting law enforcement activity in the vicinity” of Ms. Greco’s houses on Gillespie Avenue in the Pelham Bay neighborhood of the Bronx, but declined to elaborate.

A spokesman for the U.S. attorney’s office in Brooklyn said he had no comment.

A prominent fund-raiser for Mr. Adams during his mayoral campaign, Ms. Greco was appointed as his director of Asian affairs after he took office. It was not immediately clear on Thursday whether she had an attorney. She could not be reached for comment.

Fabien Levy, a spokesman for Mr. Adams, said that Ms. Greco was on leave from her City Hall job on Thursday. He said that Mr. Adams had not been accused of any wrongdoing.

“Our administration will always follow the law, and we always expect all our employees to adhere to the strictest ethical guidelines,” Mr. Levy said in a statement. “As we have repeatedly said, we don’t comment on matters that are under review, but will fully cooperate with any review underway.”

The searches of her properties, which were first reported by News 12 in the Bronx, occurred months after the homes of other associates of Mr. Adams were raided by federal officials as part of a broad public corruption investigation. That investigation has focused on whether Mr. Adams’s 2021 mayoral campaign conspired with the Turkish government to receive illegal foreign donations.

On Nov. 2, federal agents conducted coordinated searches at the homes of Brianna Suggs, the mayor’s chief fund-raiser; Rana Abbasova, an aide in Mr. Adams’s international affairs office; and Cenk Öcal, a former Turkish Airlines executive who served on the mayor’s transition team.

Vito Pitta, a lawyer for Mr. Adams’s campaign, said in a statement: “The campaign has always and will always follow the law. It would be inappropriate to comment on an ongoing investigation at this time.”

Nicole Hong contributed reporting.